Endovascular treatment can be performed using a high-performance catheter such as a balloon catheter and a stent. An intravascular ultrasound (IVUS) apparatus has been used for preoperative diagnosis or for confirmation of postoperative results. In addition, instead of the IVUS apparatus, an optical coherence tomography (OCT) apparatus has been used. As an improved OCT apparatus, a swept-source optical coherence tomography (SS-OCT) apparatus utilizing wavelength sweeping has been used. A vascular diagnosis apparatus which can acquire a tomographic image, such as the IVUS apparatus and the OCT apparatus, is used in order to obtain more detailed information of a lesion site confirmed by an X-ray apparatus, for example, a stenosed rate in blood vessels, presence of plaques in bifurcated blood vessels, or calcification distribution.
In a case where a physician determines that treatment is required, the physician observes a blood vessel tomographic image obtained by the above-described vascular diagnosis apparatus, thereby determining treatment details, for example, such as where to locate an edge position of the stent. In a case of treating a determined treatment site, the physician performs treatment for installing a balloon or the stent while observing an X-ray image (angiography) obtained by the X-ray apparatus. Therefore, it can be a very important factor for the treatment to understand that an installation position of the balloon or the stent which is determined after the physician confirms the blood vessel tomographic image corresponds to any position on the X-ray image.
As described above, it can be important for the endovascular treatment to recognize a positional relationship between the obtained blood vessel tomographic image and the X-ray image. However, the vascular diagnosis apparatus and the X-ray apparatus are configured to include respectively different modalities. Accordingly, a physician needs to perform treatment by estimating a position on the X-ray image corresponding to the confirmed blood vessel tomographic image, while relying on a landmark, for example, such as a bifurcated position.
In order to improve accuracy in estimating the position on the X-ray image corresponding to the blood vessel tomographic image as described above, a blood vessel tomographic image apparatus is present which displays the X-ray image after capturing the X-ray image when the blood vessel tomographic image is acquired and synchronizing the X-ray image with the blood vessel tomographic image. In general, a radiopaque marker is installed in the vicinity of a sensor in a catheter connected to the blood vessel tomographic image apparatus. The blood vessel tomographic image and the X-ray image are displayed in synchronization with each other, thereby improving the above-described estimation accuracy. If this function is used, the blood vessel tomographic image and the position of the radiopaque marker on the X-ray image can be visualized through one-to-one correspondence.
Furthermore, in recent years, a technique has been developed which further improves visibility by automatically detecting and highlighting the radiopaque marker from the X-ray image (refer to U.S. Pat. No. 7,930,014). However, a position of the blood vessel displayed on the X-ray image varies due to influence of heartbeats or breathing with the lapse of time. Furthermore, there is a big individual difference in the number of bifurcated human blood vessels or a configuration the bifurcated blood vessels. In some cases, many bifurcated blood vessels are present around a target blood vessel. For these reasons, an automatic detection rate of the radiopaque marker on the X-ray image is not satisfactorily high.